1. Field of the Invention
The present invention relates to a seal checker configured to conduct a seal check of packaging bags by pressing the packaging bags. Furthermore, the present invention belongs to the technical field of quality inspection of packaging bags.
2. Background Information
Generally, a packaging bag in which contents such as snack foods are packaged is subjected to a seal check in order to detect bags whose contents may quickly deteriorate due to a faulty seal. One device that conducts such a seal check is, for example, the seal checker disclosed in Japan Patent Application Publication No. 2003-156403.
With the seal checker disclosed in Japan Patent Application Publication No. 2003-156403, in the course of conveying a packaging bag supplied from the upstream side of the seal checker while sandwiching the packaging bag between upper and lower transfer conveyors, the seal checker will press the packaging bag with a pressing member mounted on the upper transfer conveyor, and detect the displacement of the pressing member or the reaction force to the pressure which acts on the pressing member at the time of pressing, and thereby conduct the seal check of the packaging bag.
In order to ensure an escape path for the air and the like inside the packaging bag to the exterior thereof when the packaging bag is pressed, the conveying belt on the upper transfer conveyor side is formed from a mesh material, and the top panel that presses the packaging bag via the belt comprises a number of grooves inclined in a direction different from the conveyance direction. Accordingly, if there is a faulty seal, the air and the like inside the packaging bag will not be blocked and will quickly leak to the exterior at the time of pressing, and therefore the seal check of the packaging bag will be properly conducted.
In addition, with the seal checker described in the above-described patent publication, for example, as shown in FIG. 13, a packaging bag X is supplied between upper and lower transfer conveyors A, B with a vertical seal portion X1 facing a top panel C disposed above. In this case, even when an upper conveying belt D is formed from a mesh material and the top panel C comprising a number of grooves C1 . . . C1 inclined in a direction different from the conveyance direction is used, the vertical seal portion X1 will still be pressed by the top panel C via the conveying belt D, and the top panel C may cover the vertical seal portion X1 having a defect therein. Further, even if there is a pinhole under the vertical seal portion X1 indicated by arrow Y, the vertical seal portion X1 will be pressed down by the top panel C, so that the escape path for air and the like may be blocked. Therefore, it is still difficult to reliably detect a faulty seal in the vertical seal portion X1 and the portion Y covered by the vertical seal portion X1.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved seal checker capable of reliably detecting a faulty seal at a seal portion or a portion covered by the seal portion, and particularly in a vertical seal portion or a portion covered by the vertical seal portion of a packaging bag. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.